Do you feel a sense of dread when the ink runs out of your favorite Steel ballpoint pen? Have you scoured every store near you, trying to find this darn refill to no avail? Worry no more! This refill is intended for the bestselling F-301 Retractable Ballpoint Pen, 1.0mm (pictured below), not to be confused with our F-301 (0.7mm point size) or F-301 Bold (1.6mm point size). If you're unsure of which point size to buy, you may refer to the barrel of your pen.